50-60 ft lbs seems pretty light. Everything I've seen has lug nuts around 90-100 ft lb, but a
generic bolt torque chart recommends about 55-60 ft lb on a 7/16 diameter bolt. I think the tapered seat on the lug nuts create more resistance, so a higher torque would logically be required to get the right bolt tension.
If someone has an era-specific owner's manual, it would likely be in that.
